IE43039B1 - Diapers - Google Patents

Abstract

1535607 Disposable diapers COLGATEPALMOLIVE CO 15 July 1976 [31 July 1975] 29544/76 Heading B5N A disposable diaper comprises, in order, a water-pervious layer 12, a spongy resilient and compressible hydrophobic fibrous layer 14, an absorbent core 16 and a water-impervious layer 24; the hydrophobic fibrous layer having a density of from 0À01 g./c.c. to 0À03 g./c.c., when not compressed, and comprising non- woven, hydrophobic fibres having an average length of from about “ inch to 3¢ inches, the fibres being bonded together at at least a sufficient porportion of their points of contact for the layer to be self-sustaining, the hydrophobic layer in the uncompressed condition being pervious to fluid but when compressed being substantially impervious to fluids. The water-pervious layer 12 has perforations 26 and is formed of non-absorbent, soft, non- woven tissue. The hydrophobic layer 14 is formed of polyester fibres derived from ethylene glycol and dimethyl terephthalate which are bonded together by adhesive or by heating. When uncompressed the layer 14 is 3/16 to ¢ inch thick. The absorbent core 16 comprises an absorbent fluff material 22, e.g. wood fluff, sandwiched between absorbent sheets, or may comprise a plurality of plies of creped cellulose or a plurality of plies of paper having a fluff coating thereon. The water-impervious layer 24 comprises a resinous film-forming polymeric material, e.g. a polyethylene. polypropylene or polyvinyl chloride.

Description

This invention relates to disposable diapers. Disposable diapers comprising an absorbent core sandwiched between water-pervious and water-impervious outer layers are well known. One of the more serious drawbacks of such disposable diapers as well as cloth diapers is their inability effectively to prevent rewetting, i.e. recontacting of waste fluid contained in the absorbent core with the infant's skin. Thus, due to the weight and activity of the infant, a portion of the fluid is squeezed out of the absorbent core, the fluid readily penetrating the adjacent water-pervious layer and thus contacting the infant's skin. This results in considerable discomfort for the infant leading to diaper binding in the crotch area in particular, and diaper rash.

Attempts to mitigate the foregoing problems include the provision of diapers having a pleated conthe struction to enhance/absorptive capacity of the diaper.

Such diapers of substantially rectangular configuration and having spaced-apart panels are usually of an undue width which allows the infant's legs to force the diaper downwardly so that it tends to sag away from the trunk of the body. This prevents proper utilization of the absorption capabilities of the diaper. Moreover, due to the spaced-apart position of the folded panels, and the consequent inefficient transfer of waste fluids to the absorbent core, rewetting of the water-pervious sheet adjacent the skin of the infant is practically unavoidable.

An object of the invention is to provide a 2. 39 diaper of the disposable type ’wherein the foregoing disadvantages are eliminated or at least mitigated to a substantial extent.

According to the present invention a disposable . diaper comprises, in order: a water-pervious layer; a spongy, resilient and compressible hydrophobic fibrous layer; an absorbent core; and . a water-impervious layer; wherein the hydrophobic fibrous layer has a density, when uncompressed, in the range from 0.01 g/cc to 0.03 g/cc and comprises non-woven, hydrophobic fibres having an average length in the range from 1/4 inch to 3i inches, · the fibres being bonded together at at least a sufficient proportion of their points of contact for the layers to be self-sustaining, the hydrophobic fibrous layer in the uncompressed condition being pervious to fluids but when compressed being substantially Impervious to fluids.

. This imperviousness is provided by the compressed fibres intermeshing to form a fluid seal or barrier.

A disposable diaper having the said arrangement of parts is capable of minimizing contact of waste fluid material in the absorbent core portion of the diaper . with the infant’s skin, to thus maintain the infant in a drier condition. The diaper can also provide improved fit, particularly in the crotch region of the diaper.

It can also provide improved air circulation in the diaper cover area, affording an air cushion feel for the . infant. 3The invention may be performed in various ways, and an embodiment trill now be described by way of example with reference to the accompanying drawings, wherein: Figure 1 is a fragmentary cross-section of a diaper embodying the Invention; and Figure 2 is a fragmentary exploded perspective view of the diaper.

The diaper 10 has four main component parts, namely a water-pervious layer 12, a hydrophobic fibrous layer 14, an absorbent core 16 comprising an absorbent layer or layers 22 between absorbent sheets 18 and 20, and a water-impervious layer 24.

The water-pervious layer 12 may be a non-absorbent soft, non-woven tissue which may have a large number of small perforations 26. This layer is readily waterpervious and facilitates passage of waste fluid toward the absorbent core 16. The water-pervious layer 12 is positioned adjacent the skin of the infant wearing the diaper and for comfort should be soft and non-irritating. Thus, the water-pervious layer 12 may be made of paper or of any of a wide variety of non-woven webs having the desired properties of softness to the touch, often termed hand or feel, porosity and hydrophobic action with respect to fluid. Materials suitable for such use are well known in the art.

The hydrophobic fibrous layer 14 may be prepared from film-forming, resinous materials of various well known types. These include, for example, a resinous polyester comprising the reaction product of ethylene .glycol 4. 3 0 30 and dimethyl terephthalate, e.g. resinous polyesters such as those marketed under the trade marks DACRON, VYCRON KODEL and TERYLENE.

Particularly preferred is the resinous polyester · fibre material commercially available from J.P. Stevens Nonwoven Inc. U.S.A. under the trade name designation Bondaire. This material comprises the reaction product of ethylene glycol and dimethyl terephthalate spray bonded with a heat- resistant binder, such as the product commercially . available in U.S.A. known as Firegard, to provide a resilient, fibrous pad structure.

The fibres used in preparing the fibrous layer 14 have an average length in the range from 1/4 inch to 3# inches. In order to attain the desired properties regarding . resiliency, sponginess and compressibility, layer 14 when uncompressed has a density in the range from 0.01 g/cc to 0.03 g/cc.

The resultant layer possesses a void volume, i.e. a ratio of free space volume to fibre volume, which tends . to assure proper functioning of the layer 14.

Preferably the layer 14 when uncompressed has a thickness in the range from 3/16 inch to £ Inch. If the layer 14 is thinner than this the desired fluid sealing action which obtains by virtue of fibre intermeshing upon . compression of the layer 14 may not occur. If the layer is thicker than this the diaper may he bulky, difficult to handle and uncomfortable.

The layer 14 as described can be prepared by techniques well known in the art. Thus, fibres having . the dimensions stated can be subjected to conditions of turbulence to orient the fibres at random, such as by air blowing and/or tumbling. The operation can be conducted at temperatures sufficiently high to soften . 303© the fibres, resulting in a fusion of the fibres at at least a substantial proportion of their points of contact. Alternatively, the fibres may be treated with an adhesive bonding agent, such as by spraying, to provide . the desired fibrous structure. Adhesives suitable for such use are well known in the art and include, for example, the products Mycar 2671 (B.F, Goodrich) and E771 (Rohm and Haas) commercially available in U.S.A.

The fibres comprising the layer 14, due in large ). part to their hydrophobic character, are substantially form-retaining while exhibiting effective flexibility, resiliency and compressibility, i.e. spring-back characteristics, despite exposure to substantial quantities of body fluid waste. The water-sealing characteristics of . the fibrous layer 14, as it applies to the prevention of rewetting, may be explained as follows. With the diaper in place on the infant, the water-pervious layer 12 is adjacent the infant’s skin. When the infant urinates, the urine passes through the water-pervious layer 12 and . the fibrous layer 14 into the absorbent core 16 where it is absorbed by the sheets 18 and 20 and the layer or layers 22. The weight of the infant tends to compress the layer 14 causing the fibres to become intermeshed. This substantially reduces the void volume of the layer 14 to . the extent of forming a seal or barrier against re-entry of urine from the absorbent core 16 into the waterpervious layer 12.

The problem of urine re-entry is particularly acute in those areas of the diaper subjected to the infant's weight. However, in these areas the barrier 6. effect of the layer 14 is most pronounced and effective. Although the layer 14 where compressed can form a barrier to the flow of urine to the absorbent core, it has been found in practice that the urine nevertheless readily . passes into the absorbent core 16, particularly through those relatively less-compressed areas of the layer 14 immediately adjacent the compressed portion of the layer 14.

The absorbent core 16 can comprise an envelope type construction including absorbent sheets or layers . 18 and 20 filled with a fibre fluff 22 such as wood fluff or cotton fluff. This envelope can be formed after blowing the absorbent fluff material as a coating onto either or both of the absorbent sheets 18 and 20. These sheets may be absorbent paper such as paper tissues. 15i Alternatively, the absorbent core 16 may comprise a plurality of plies of paper having a fluff coating thereon or plies of creped cellulose or wadding.

The layer 24 is made of a suitable waterproof, nonabsorbent material, preferably a resinous film-forming . polymeric material, which Is liquid-impervious for preventing liquid from passing right through the diaper.

The layer 24 is preferably made of a polyethylene film.

Other suitable materials Include, for example, polypropylene and polyvinylchloride.

Claims (11)

1. WHAT WE Claim Is:1. A disposable diaper comprising, in order: a water-pervious layer; a spongy, resilient and compressible hydrophobic fibrous layer; an absorbent core; and a water-impervious layer; wherein the hydrophobic fibrous layer has a density, when uncompressed, in the range from 0.01 g/co to 0.03 g/cc and comprises nonwoven, hydrophobic fibres having an average length in the range from 1/4 inch to inches, the fibres being bonded together at' at least a sufficient proportion of their points of contact for the layer to be self-sustaining, the hydrophobic fibrous layer in the uncompressed condition being pervious to fluids but when compressed being substantially impervious to fluids.

2. A disposable diaper in accordance with Claim 1 wherein the water-pervious layer comprises non-absorbent, soft, non-woven.tissue.

3. A disposable diaper In accordance with Claim 1 or Claim 2 wherein the water-pervious layer is provided with a plurality of perforations.

4. A disposable diaper in accordance with any of the preceding Claims wherein the hydrophobic fibrous layer comprises resinous polyester fibres derived from the reaction product of ethylene glycol and dimethyl terephthalate. 8.

5. · A disposable diaper in accordance with any of the preceding Claims wherein the fibres of the hydrophobic fibrous layer are adhesively bonded together.

6. A disposable diaper in accordance with any of the 5 preceding Claims wherein the hydrophobic fibrous layer when uncompressed has a thickness in the range from 3/16 inch to £ inch.

7. A disposable diaper in accordance with any of the preceding Claims wherein the absorbent core comprises 10 an absorbent fluff material sandwiched between absorbent sheets.

8. A disposable diaper in accordance with any of Claims 1 to 6 wherein the absorbent core comprises a plurality of plies of creped cellulose. 15

9. A disposable diaper in accordance with any of the preceding Claims wherein the water-impervious layer comprises a resinous, film-forming polymeric material.

10. A disposable diaper in accordance with Claim 9 wherein the material of the impervious layer is 20 polyethylene, polypropylene or polyvinylchloride.

11. A disposable diaper substantially as described with reference to the accompanying drawings.